Holothrix Rich. ex Lindl.

First published in Gen. Sp. Orchid. Pl.: 257 (1835), nom. cons.
This genus is accepted
The native range of this genus is Tropical & S. Africa, SW. Arabian Peninsula.

Descriptions

General Description

Terrestrial herbs with small, ovoid or ellipsoid tubers. Leaves radical, 1-2, appressed to ground, sessile, ovate or orbicular, sometimes withered by flowering time. Inflorescence erect, unbranched, with or without sheaths, sparsely to densely flowered. Flowers sessile or shortly stalked, often secund. Sepals subegual, free, sometimes setose, often hairy, usually green. Petals usually longer (often much longer) than sepals, entire or lobed, often rather fleshy. Labellum lobed or toothed, rarely entire, spurred; adnate to column at base. Column short; anther loculi parallel; pollinia two, granular; caudicles short; viscidia mall, naked; stigma sessile. (PC).

Distribution

A genus of 50-60 species in tropical Africa, South Africa, and tropical Arabia. (PC).

Ecology

Members of the terrestrial genus Holothrix grow in a variety of habitats across its range in both exposed and shaded conditions. For example, the distribution of the 25 Holothrix species from South Africa encompasses the semi-arid regions of the Karoo and Namaqualand and the winter-rainfall area of the south-western Cape Province, to the forests and grasslands in the summer-rainfall areas of the eastern Cape Province, Natal, and the Transvaal (Schelpe 1966). In other areas such as Zambia, Malawi, and Tanzania, Holothrix is typically found in Brachystegia (Fabaceae) woodland and in dry grassland in the submontane or montane zones at elevations ranging from 1300-2300 m, where it often appears after the grass has been burned (la Croix and Cribb 1995). Plants are frequently located near boulders or among rocky areas that offer some shade or are sites of water seepage. In southern Africa H. orthoceras Rchb.f. is said to be often found among moss-covered rocks, H. macowania Rchb.f. in shallow soils near granite boulders, and H. johnstonii Rolfe and H. longiflora Rolfe on slabs of rock and in crevices in seepage slopes (la Croix and Cribb 1995). In Saudi Arabia, H. arachnoidea Rchb.f., which is widespread along the escarpment in the Asir and southern Hijaz, always occurs in shade, including the shade of boulders (Collenette 1985).
The main flowering season for Holothrix is the spring and summer. Prior to flowering, the slender stem and pair of leaves that typically lie flat to the ground arise from the small ovoid or ellipsoid underground tubers. Although the leaves usually do not senesce before the flowers open, this does occur in some species such as H. thodei Rolfe (Schelpe 1966). The formation of fruits in Holothrix has been recorded from some herbarium specimens collected from southern Africa (la Croix and Cribb 1995). (RN).

[O-EM]

Orchidaceae, I. la Croix & P.J. Cribb. Flora Zambesiaca 11:1. 1995

Morphology General Habit
Terrestrial herb with small ovoid or ellipsoid tubers.
Morphology Leaves
Leaves radical, 1–2, appressed to ground, sessile, ovate or orbicular, sometimes withered by flowering time.
Morphology Reproductive morphology Inflorescences Scape
Scape erect, unbranched, with or without sheaths.
Morphology Reproductive morphology Flowers
Flowers sessile or shortly stalked, often secund.
Morphology Reproductive morphology Flowers Calyx
Sepals subequal, free, often hairy, usually green.
Morphology Reproductive morphology Flowers Corolla
Petals usually longer (often much longer) than sepals, entire or lobed, often rather fleshy.
Morphology Reproductive morphology Flowers Labellum
Lip lobed or toothed, rarely entire, spurred; adnate to column at base.
Morphology Reproductive morphology Flowers Column
Column very short; anther loculi parallel, pollinia granular; caudicles very short, viscidia small, naked; stigma sessile.
[FZ]

Orchidaceae, V. S. Summerhayes. Flora of Tropical East Africa. 1968

Morphology General Habit
Terrestrial herbs with small ovoid or ellipsoid tubers and 1 or 2 sessile ovate or orbicular radical leaves
Morphology Reproductive morphology Inflorescences Scape
Scape erect, with or without sheaths, unbranched
Morphology Reproductive morphology Flowers
Flowers often secund, sessile or shortly stalked
Morphology Reproductive morphology Flowers Calyx
Sepals subequal, free from one another, often hairy, thin in texture
Morphology Reproductive morphology Flowers Corolla
Petals usually longer (often much longer) than sepals, entire or divided in the upper part into 3 or more finger-like lobes, rather fleshy
Morphology Reproductive morphology Flowers Labellum
Lip similar to petals but broader with more lobes, spurred at the base, adnate to the column
Morphology Reproductive morphology Flowers Column
Column very short; anther-loculi parallel, pollinia granular, caudicles very short, viscidia small, naked; stigma sessile.
[FTEA]

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit
Terrestrial herbs with small ovoid root tubers and 1 or 2 sessile ovate to orbicular radical leaves
Morphology Reproductive morphology Inflorescences Scape
Scape an erect raceme with sessile or shortly stalked and often secund flowers
Morphology Reproductive morphology Flowers Calyx
Sepals entire
Morphology Reproductive morphology Flowers Corolla
Lip similar to lateral petals but broader with more lobes and spurred at base Lateral petals entire or divided into 3 to many lobes
Morphology Reproductive morphology Flowers Column
Column very short with 2 sectile pollinia.
Distribution
About 45 species in tropical and subtropical Africa with two species extending to Arabia.
[FSOM]

Ecology

Orchids belonging to the South African endemic genus Bartholina are terrestrial species, for which the distribution extends from the south-western and southern Cape Province to the semi-arid Namgualand to the southern borders of the Great Karoo. The most common species is B. burmanniana, which can form extensive colonies on pebbly ground on the veld. Bartholina etheliae is much rarer, and normally only small colonies or individual plants are found growing under shrub by vegetation. It flowers from October to January after a period of summer dormancy during the dry period, the aerial stem arising from the small, spherical tuber underground prior to anthesis. The flowering period of B. burmanniana is earlier, between August and November, depending on the aspect of the habitat. In this species, the occurrence of flowering is promoted by fires on the veld (Schelpe 1966). (RN).

Distribution

A small genus of two species in Cape Province of South Africa. (JW).

General Description

Dwarf, terrestrial herbs growing from ovoid-oblong tubers. Leaf solitary, prostrate, fleshy, reniform-orbicular, amplexicaul, hairy. Inflorescence one-flowered; scape hairy, lacking sterile bracts; bract lanceolate, much shorter than the the ovary, hairy or glabrous. Flower large for plants, resupinate, spidery; pedicel and ovary curved, hairy or glabrous. Sepals subsimilar, free, erect, green, hairy or glabrous. Petals erect, falcate or sinuous, lanceolate, adnate to the dorsal sepal, white or green, glabrous. Labellum much larger than the sepals and petals, spreading-deflexed, three-lobed, glabrous, spurred at the base, white with white or green lacerae; lobes deeply lacerate, tapering or clavate at the tips of each division; spur short, shorter than the ovary, tapering-conical. Column erect; anther loculi subparallel, connivent toward apex, the connective not distinct; pollinia two, clavate with elongated caudicles, coarsely granular; viscidia two, small, reniform; rostellum three-lobed, the mid-lobe short, reflexed, the side lobes sessile; stigma sessile. (JW).

[O-EM]

Sources

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of Somalia

    • Flora of Somalia
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Herbarium Catalogue Specimens

    • 'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Orchideae: e-monocot.org

    • All Rights Reserved